The invention relates to a reproducing arrangement for the reproduction of compressed data included in data blocks of a received data stream, the compressed data received being reproduced only partly in a multi-speed reproducing mode of the reproducing arrangement.
Such a reproducing arrangement of the type defined in the first paragraph is known from the document EP 0 777 383 A1 and takes the form of a data receiving device. The document EP 0 777 383 A1 further discloses a data transmitting device adapted to compress and encode audio/video data. Audio/video data thus compressed and encoded are inserted as payload into data blocks of a serial data stream by the data transmitting device and transmitted to the data receiving device.
The known data receiving device has data block detection means for detecting the data blocks of the data stream and read means adapted to read the compressed and encoded audio/video data from the detected data blocks. After decoding the compressed audio/video data are decompressed by decompression means of the data receiving device and are stored in memory sections of a reproduction memory of the data receiving device. When the data receiving device is in the normal-speed reproducing mode reproducing means are adapted to read out all the audio/video data stored in the reproduction memory and to reproduce this audio/video information, as a result of which a reproduction of the audio/video information at the normal reproducing speed is obtained.
The known data transmitting device further includes a reproduction data use generator which is adapted to generate reproduction use data and to insert the reproduction use data into the payload of the data blocks. The reproduction use data identify the normal speed reproducing mode or a multi-speed reproducing mode as well as memory sections of the reproduction memory from which audio/video data are to be read in accordance with the specified reproducing mode.
When for example reproduction use data identifying a double speed reproducing mode are received the known data receiving device is adapted to read stored audio/video data from every second memory section of the reproduction memory. In this mode audio/video data are read and reproduced from every second memory section, as a result of which a reproduction of the audio/video information at the double reproducing speed is obtained.
With the known reproducing device it has proved to be a disadvantage that in the multi-speed reproducing modes all the received, compressed and encoded audio/video data of the payload must also be decoded, decompressed and stored in the reproduction memory although, depending on the specified multi-speed reproducing mode, only a part of the audio/video data stored in the reproduction memory will actually be reproduced. This is unfavorable in particular because the decompression of the compressed audio/video data involves a very high computing capacity and, consequently, a substantial real-time occupation of the decompression means.
It is an object of the invention to provide a reproducing arrangement in which only those compressed data received in data blocks have to be decompressed which will actually be reproduced in the specified multi-speed reproducing mode. In order to achieve this object characteristic features in accordance with the invention are provided in such a reproducing arrangement, in such a manner that the reproducing arrangement can be characterized in the manner defined hereinafter.
A reproducing arrangement for the reproduction of compressed data included in data blocks of a data stream, each data block of the data stream including header information, and the compressed data included in a data block being decompressible and reproducible independently of the compressed data included in other data blocks of the same data stream, and the sequence of the data blocks in the data stream defining the sequence of reproduction of the compressed data included in the data blocks, the arrangement having data block detection means adapted to detect the header information of each data block of the data stream when the reproducing arrangement is in the reproducing mode, and having read means for reading the compressed data included in a detected data block, and having decompression means for decompressing the compressed data read by the read means and for supplying decompressed data, and having reproducing means for reproducing the decompressed data supplied, and having mode means for defining a normal speed reproducing mode, in which the compressed data of all the data blocks included in the data stream are read by the read means and supplied to the decompression means, and for defining a multi-speed reproducing mode, in which only compressed data of part of the data blocks included in the data stream are read by the read means and supplied to the decompression means.
In this way, it is achieved that data block detection means initially detect only the beginning or the end of each data block of the data stream having a high bit rate. For this detection the real-time occupation of the detection means is comparatively moderate. Depending on the selected or specified multi-speed reproducing mode the read means read only those compressed data from the detected data blocks and supply said data to the decompression means for decompression, which should actually be reproduced as information in this multi-speed reproducing mode. This has the advantage that the computing capacity of the decompression means provided for the normal speed reproducing mode is also adequate for multi-speed reproducing mode of the reproducing arrangement, in which the received or reproduced data stream has a very high bit rate.
The measures defined in claim 2 have the advantage that an audio reproducing arrangement for the reproduction of audio information in a multi-speed reproducing mode is obtained, whose decompression means require only a small computing capacity and can therefore be manufactured in a particularly cheap manner.
The measures defined in claim 3 have the advantage that the audio reproducing arrangement is adapted to reproduce audio information encoded in accordance with the MPEG1 standard and the MPEG2 standard in one of the multi-speed reproducing modes.
The measures defined in claim 4 have the advantage that the reproducing arrangement has a hard disk for the storage of the data stream, which hard disk forms a particularly cheap rewritable memory means.
The measures defined in claim 5 have the advantage that the reproducing arrangement may be connected to, for example, the internet and can thus provide on-line reproduction of a data stream received from a data server, connected to the internet, in the multi-speed reproducing mode to give the user an overview of the content of the data stream being received.
The above-mentioned as well as further aspects of the invention will become apparent from the embodiments described hereinafter by way of example and will be elucidated with reference to these examples.